This is just a hunch based off of your apparent knowledge and skill with the engines in question - I would say there is a port issue of some sort at work here. Either cross talk or crankcase bleed off and/or a blowdown or uneven transfer port timing issues... or any combination therein.
I say this because my iron sleeved 110cc engine, while a bit apples to oranges, had all sorts of port issues similar to what you describe. The piston blocking the exhaust port by about a third and terrible exhaust duration to incredibly small and uneven transfer timing and durations with piss poor blowdown. The only thing even remotely "good" on the entire thing was the intake side and I use that word loosely. If we pretend it had good compression and squish... which it didn't, it would have never made any meaningful power anyway.
I totally agree. That has to be the case. I found it a bit odd that after port matching the first sleeve to the jug and it performing poorly, then trying a new jug from a different more trustworthy supplier, and simply cleaning up the slag that performance it unchanged. So that led me to believe maybe a recent change/manufacturing issue.
I wanted to confirm others port maps to see if perhaps there has been a flub up recently in manufacturing that has the ports way off.
The 2 jugs are from the same factory. They have the little woodpecker logo cast into them both, and identical other than the CDH jug has a bit more sleeve overhang.
I tried all day today going back through the entire process of elimination with various components to try to eliminate myself as the problem. Only thing being constant is the bottom end, which is seemingly 100% OK. Not much to go wrong there other than a massive leak through crank seals, case gasket etc. , and case pressure seems OK.
No go. These 2 49mm steel sleeve jugs just will not perform.
I would at least expect a minimally noticeable difference between the port matched and decked one vs the "dirty" one. The fact there isnt seems to me that the ports are simply off, even in the aluminum jug casting so no amount of matching the sleeve to the casting is going to help.
I will degree the ports out on these as well.
Its a damn shame too as it runs smooth as silk on both jugs.
.......I too buy the problem child (or that needs some work) stuff. I am nobody if I dont have something to work on.
EDIT: .......BTW, The transfers are the same height. When I matched the first jug I made sure they were identical. Within .005" to be exact. On the second that I just cleaned up, they are within about .07in. Not perfect, but certainly doesnt account for the problem especially since a perfectly matched one performs the same.